[Nitrates in heart failure: the hemodynamic effects and clinical implications]

It is a common opinion that nitrate therapy may have a harmful effect on cardiac output in patients with congestive heart failure when left ventricular filling pressure is markedly reduced. In this study, we evaluated, using hemodynamic monitoring with Swan-Ganz catheterization, the effects on cardiac output and filling pressures of high-dose intravenous nitroglycerin in 8 patients with dilated cardiomyopathy and severe heart failure. At maximal doses of nitroglycerin utilized (350 +/- 220 micrograms/m, range 100-800), a significant reduction in right atrial pressure (from 4 +/- 3.5 to -1 +/- 4 mm Hg, p < 0.001) and pulmonary capillary wedge pressure (from 16 +/- 5 to 7 +/- 3 mm Hg, p < 0.001) was observed. Furthermore, we found neither a significant reduction in systemic vascular resistances (from 1,500 +/- 329 to 1,320 +/- 330 dynes/s/cm-5) nor changes in heart rate or blood pressure. Finally, stroke volume and cardiac index increased slightly although not significantly (from 62 +/- 18 to 70 +/- 16 ml and from 2.3 +/- 0.45 to 2.65 +/- 0.4 l/m/m2). The preservation of stroke volume despite a marked reduction in left ventricular filling pressure can be explained by a reduction in pericardial constraint and of mitral regurgitation induced by nitroglycerin. The clinical implications of these hemodynamic results are discussed with emphasis on the short- and long-term use of nitrates in congestive heart failure.